The Pharmacogenetics and pharmacogenomics Knowledge Base (PharmGKB) is designed to catalyze research on how genetic variation contributes to variation in drug response. It provides information and analytical tools by means of a public website that is devoted to linking genotype and phenotype information in the post-genome era. The PharmGKB development team has five foci: user interface &functionality, data curation, outreach &dissemination, administration, and infrastructure. This proposal is based on four years of experience working with the scientific community to define and prioritize opportunities to support pharmacogenetics and pharmacogenomics. The PharmGKB has accumulated genotype data, phenotype data, curated literature annotations, and drug-related pathways-and currently attracts more than 23,000 unique visitors (IP addresses) each month. Our plan stresses 1) extending the PharmGKB to the entire scientific community by increasing data submissions, functionality, and ease of use, 2) focusing on acquiring high-quality drug-related pathways and using them as interfaces to, pharmacogenetic data and knowledge, 3) catalyzing the use of standards for information exchange within the field, and 4) participating in the public discussion of methods to protect the privacy and confidentiality of study subject data.